Rheostat



Nw. 3I 1925. 1,560,405

Y( F. A. cALKlNs RHEOSTAT Filed Jan. .28, 1924 2 Sheets-Sheet l @(+4 1g 2:9 1519 11 25 rns 15 z? Z7 C i- 26 ZZ' Z'Z- Z6 5 30 Z9 79 50 f f 6 j; /ZO 7 ZZ fg 70 IZ E 4 f 16 g j 18 v l L.: ,l I

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F. A. CALKINS RHEO S TAT Filed Jan. 28. 1.924v 2 Sheets- Sheet 2 WITNESS:

Patented Nov. 3, 1925.

UNITED STATES FREDERICK A. CALKINS, OF MCKENZIE, NOR-TH DAKOTA.

RHEOSTAT.

Application filed January 28, 1924A To o?? coton? it m concern Be it known that I. Fnnnnnion A. CarliiNs, a citizen ot the United States. residing at McKenzie, in the county ot Burleigh and State ot North Dakota, have invented new and useful impro nents in Bheostats, ot which the following is a specitication.

This invention relates to electrical control devices, particularly to rheostats, and has for its object the provision of a novel device of this character designed particularly for use in controllingF current to the iilament of a vacuum tube used in radio reception, the construction being such that a very accurate and delicate adjustment may be had so that the best results may be obtained from even the most critical tubes.

An important object is the provision of a device ot this character which is so constructed that the current may be split so that the devicewill actthe same as two rheostats.

another object is the provision of a device of this character which will be simple and inexpensive in manufacture, easy to adjust, positive in action, efficient and durablein service and a general improvement in the art.

lith the above and other objects and advantages in view the invention consists in the details ot construction to be hereinafter more Jfully described and claimed and illustrated in the accompanying drawings, in which:

Figure 1 is a it'ront elevation,

Figure 2 is a top plan view,

Figure 3 is a rear elevation,

Figure 4 is a longitudinal section on the line 4-4 of Figure 2,

Figure 5 is a cross section on the line 5 5 Vof Figure 2,

Figure 6 is a cross section on the line 6 6 of Figure 2,

Figure 7 is a ldetail perspective view of one of the conductor arms,

Figure 8 is a detail perspective view of the slider,

Figure 9 is a detail section showing the device mounted upon a panel,

Figure 10 is a diagram of a circuit arrangement,

Figure 11 is a diagram of a. modified circuit.

Referring more particularly to the drawings I have shown the device as comprising front and back plates or panels 10 and 11 Serial No. 689,167.

which may be constructed ot balfclite or any other suitable insulating material and of any proper size and shape. These members are connected by spaced parallel rods 12 secured in any desired manner tor iustance by means ot nuts 13 threaded thereon. Journaled centrally through both panel members 10 and 11 is a screw 14 having'- one end carrying a pinion 15 and its other end equipped with a control knob 1G. it is really intended that this entire device be mounted at the rear of the supporting panel of a radio set and tor this reason the front member 10 is preferably provided with holes 17 for the passage of suitable securing bolts or the like for effecting' mounting. For the same reason, the forward end et the sha'tt or screw 14 projects consideralily beyond the front member 10 so that the control knob 16 will be located in advance ot the supporting panel of the set. Figure 9 shows a `detail section through such a panel A having my device applied thereto and held by the bolts B. It should be understood however that the device might be provided with a base or casing so as to be an enclosed instrument not requiring panel mounting, such a change being well within the spirit ot the invention.

Journaled through the front and back members 10 and 11 at opposite sides ot the central screw 14 are supporting rods 18 ot insulating' material equipped at their rear ends with gears 19 meshing with the pinion 15 `so as to be turned when the screw 14 is turned. Secured to and wrapped about these rods or cores 18 arc high resistance wires 2O which have their ends suitably fastened so as to prevent unwinding. In actual practice one end of each wire 2O may be passed through a hole 21 in the rod 18 and bent over to effect holding, while the other end is secured to a metallic collar 22 fastened onto the rod near the associated gear 19.

At the rear side of the rear member 13 I provide three terminal clips 23, 24 and 25, the tirst one of which is connected with the screw 14, while the latter two are connected with the rods 12. Secured to each rod 12 is an arm 26 terminating in a Jfork 27 engaged upon the adjacent or associated collar 22 for electrically connecting the high resistance Wires 20 with the connectors or clips 24 and 25.

Mounted on the screw 14 is a slider formed as a metal block 28 having a threaded hole into which the screw 14 is threaded. Carried by this block are laterally extending spring arms 29 which have their outer end portions curved to define contacts bearing upon the wires or coils 20. rhese contacts are preferably ribbed as shown at 30 for insuring proper contact.

In the use of the device, it is interposed in a circuit as indicated in Figure l0 which shows one terminal ot' a battery C connected by a wire D with the clip 24, with the clip 25 connected by a wire E with one lilament terminal of a vacuum tube or the like to be energized, the other terminal of which is connected by a wire F with the remaining terminal of the battery. "ln the operation it will be seen that the current will tiow from the battery, through the wire D, clip 24, associated 'rodl2, arm 26, collar 22, associated wire 20, through the slider to the other wire 2O and other forked arm to the rod l2 associated therewith and from the clip 25 through the wire E to the vacuum tube. The circuit to the filament er' the latter being completed by the wire F. lt should be mentioned that the clips 28,724 and 25 might be replaced by binding posts or their equivalent or may be replaced by simple terminal lugs to which connections may be made by soldering, all of these details being immaterial. By making a connection with the central clip 23, it is apparent that the device can be used as two rheostats though the resistance in this instance will naturally be only one-half in each circuit. In making use of this manner of connection, the connection from the battery is made to the intermediate clip 23 and the connections to the two tubes or other device to be operated should be mad-e by wires leading from the clips 24 and 25 respectively. This modified, circuit .arrangementand use ot' the device is illustrated in Figure ll.

In the operation it is apparent that by turning the knob 16, the rotation of the screw 14 will move the slider along the resistance coils, thus increasing or decreasing the length of wire in the circuit. Furthermore the rotation ot the screw turns the gears 19V and consequently the rods 18 carrying the resistance wire so that the contact of the wires with the contacts ot the slider will be continuous and the points constantly changing as the screw is turned. In actual practice have discovered that the most minute adjustments may thus be accomplished and the current varied withsuch accuracy and delicacy as to insure maximum eticiency ot the tulces even though they may be ot a highly critical type. lill'hile tubes are referred to, it is obvious that the device may be used 'for controlling electric current to any devices wherein tine adjustment is essential.

While l have shown and described the preferred embodiment ot my invention it is of course tcbe understood that I reserve the right to make such changes in the form, construction and arrangement of parts as will not depart from the spirit of the invention or the scope ot the subjoined claim.

Having thus described my invention I claim:

A device of the character described comprising front and rear members arranged in space relation, spaced parallel resistance coils liournally mounted between said front and rear members, a screw journaled centrally through said front and rear members and located between said resistance coils, intermeshing gears'on said coils and screw for effecting simultaneous rotation ot all, a slider threaded onto the screw and having its end portions bearing against saidcoils, rods secured to said `liront and rearmembers and located in spaced relation to and outwardly oit said coils, and contacts carried by said rods and bearing againstrther coils.

In testimony whereof I a X my signa- 

